This invention relates to applying labels to articles and more particularly to applying labels to containers of molded plastic composition.
In the application of labels by what is known as transfer labeling, it is customary to position labels on a web and thereafter transfer the labels to the articles to be labeled. In one type of such labeling, heat-sensitive labels are used that must be heated and applied to the articles. In another type, pressure-sensitive labels are used that must be removed from the web and applied to the article. An improved apparatus that can be readily changed for use either for applying heat-sensitive labels or for applying pressure-sensitive labels is that disclosed and claimed in U.S. Pat. No. 5,250,129 issued in the name of Terence J. Twele and assigned to Owens-Illinois Plastic Products Inc., of Toledo, Ohio, assignee of record herein, which is incorporated herein by reference.
When applying such labels to articles of molded plastic composition, particularly blow-molded plastic containers composed of high density polyethylene or the like, in accordance with conventional technology it is necessary to delay application of the labels for a prolonged period of time, such as 24 hours, after removal of the containers from the mold in which they are fabricated to allow de-gassing of the container walls. Gases are trapped within the plastic material of the container walls as a result of the fabrication process, particularly in blow molding processes, and these gases must be allowed to migrate out of the container walls before running the containers through a labeling apparatus or process. Otherwise, if a pressure-sensitive or heat-sensitive label, particularly one made of non-breathable material such as a metalized pressure-sensitive label, is placed on the container prior to de-gassing, the residual gases that migrate out of the container wall material beneath the label will create bubbles beneath the label, thereby resulting in a defectively labeled product requiring costly re-processing and/or scrapage.
Of course, the prolonged delay period required for de-gassing after molding prior to transfer labeling of such plastic articles adds to production and hence product costs, particularly in a high volume mass production set-up. The de-gassing delay period entails mechanized transport equipment, storage space requirements, and added potential for damage to the article in such de-gassing processing intermediate the molding and labeling stations.
It is also common practice in the plastic container manufacturing art to imprint labeling information indicia on mold-fabricated plastic containers by employing a silk screening operation. Upon removal from the mold, the fabricated container is placed on a conveyor and conveyed successively through several stations, at one or more of which labeling information is silk screened onto one or more exterior surfaces of the container wall. Multiple stages are employed for multiple-color labeling and decorating. Typical apparatus for printing or decorating by silk screening is shown in U.S. Pat. Nos. 4,005,649 and 4,398,627, and an improvement thereover is disclosed and claimed in U.S. Pat. No. 5,484,047 issued Jan. 16, 1996 in the name of John A. Plenzler and assigned to Owens-Illinois Plastic Products Inc., the aforementioned assignee of record herein, which is also incorporated herein by reference.
Such labeling of molded plastic articles by silk screen imprinting with typical silk screen ink materials, even when practiced on blow-molded plastic containers, does not require the aforementioned de-gassing delay period in the production process inasmuch as the labeling so applied to the container wall is inherently highly gas pervious or permeable since the ink-imprinted alphabetical and numerical characters are spaced from one another throughout the labeling and thus cover only a minor percentage of the exterior wall surface area available for out-gassing.
Accordingly, among the objectives of the present invention are to provide an improved system and method that enables conventional transfer labeling methods and equipment to be employed to apply pre-printed labels made of gas impermeable material to the appropriate surface area of the article, such as the container wall, while de-gassing from the plastic material of the article is still occurring but nevertheless preventing formation of gas bubbles beneath the applied label, thereby eliminating the need for the aforementioned de-gassing delay period between de-molding and transfer labeling and thus eliminating the attendant production cost penalties.
Another object is to provide an improved system and method of the aforementioned character that also enables conventional silk screening technology, apparatus, methods and materials to be employed during de-gassing of the molded article, and that enables composite labeling of the finished article by both silk screen and transfer labeling while still eliminating the aforementioned de-gassing delay period prior to transfer labeling.
A still further object of the invention is to provide a new and improved article of manufacture made of a molded plastic composition having silk-screen-imprinted labeling on the exterior surface thereof wherein all or a portion of such silk screen is covered by a removably attached label pre-printed with indicia that is a replicate of the silk screen imprinted indicia covered by the label, thereby enabling the article to have a label that is end-use customer removed for rebate-type return or similar merchandising promotion while thereafter still leaving the article fully labeled, thereby maximizing the available labeling surface area of the article without altering the point-of-sale trade dress of the article.
In general, and by way of summary description and not by way of limitation, the present invention achieves the aforementioned objectives by employing conventional silk screen label technology and processing shortly after container fabrication de-molding in order to deposit a layer of conventional silk screen ink over the entire predetermined area of the external container surface designated for application thereon of a self-adhering label of either the pressure-sensitive or heat-sensitive type. This silk screen ink covering of the label receiving area of the container surface customarily drys very quickly so that the self-adhering label may be transfer applied over the silk screen area immediately after silk screening and even while out-gassing is still occurring from the molded article. However, the silk screen ink layer is sufficiently gas impermeable so as to prevent migration of gases out of that portion of the container exterior surface disposed beneath the applied label, and hence this protective ink barrier in turn prevents formation of bubbles beneath the label. Those gases in the container wall resident beneath the label-affixed area can then nevertheless out-gas by migrating out of the internal wall surface from the interior of the container and/or from the marginal exterior surface area surrounding the labeled area. Preferably the silk screen ink layer deposited beneath the self-adhering label is clear (non-pigmented) and compounded to be non-transmissive to ultraviolet energy.
It is also contemplated in accordance with the present invention to provide a silk screen imprinted label on the container beneath the transfer-applied self-adhering label. In this embodiment, the gas-blocking ink layer is silk screened over the silk screened label imprinting, and then the self-adhering label transfer applied over the gas-blocking layer of ink. This provides a new article of manufacture in which the self-adhered label may be xe2x80x9cpeelablexe2x80x9d by a customer for return to obtain a rebate, for example, without thereby altering the contents of the labeling information remaining on the container after removal of the peelable label. Hence the xe2x80x9ctrade dressxe2x80x9d of the article need not be altered in order to provide a peelable label on the same, and the available surface area available for labeling is thus maximized.